1. Field of the Invention
This invention aims to provide a wireless communication medium processing apparatus and a wireless communication medium processing system which are of a very few apparatus, equipment configuration, and are optimum on the occasion of carrying out recognition of an ID code etc. simultaneously by carrying out reading, or writing, or reading/writing simultaneously with a single or a plurality of wireless communication media, in a wire area, or a number of different places.
2. Description of the Related Art
For the purpose of authentication and destination sorting of baggage and so on, it has become frequent to use a wireless communication medium having an ID code, such as an IC card and an IC tag, and a wireless communication medium processing apparatus for carrying out ID code authentication. When a communication mounted medium exists within a communication range of a communication mounted medium processing apparatus, an induced voltage is generated on an antenna which a wireless communication medium has, due to a magnetic field from the antenna, and this voltage is rectified and electric power and transmission data are supplied. In the wireless communication medium to which electric power was supplied, a switch is turned ON, OFF, in accordance with data which was read out from a memory mounted, for example, by a modulation circuit which is composed of a load resistance and a switch which were connected to the antenna, in accordance with 1, 0 of data. By this ON, OFF, there occurs load fluctuation to an antenna which the wireless communication medium has, and this load fluctuation is transmitted to an antenna on the side of a communication medium processing apparatus, as a signal. The transmitted signal is demodulated, and its ID code authentication is carried out (e.g., see, JP-A-2003-162696 publication).
At this time, in case of carrying out in/out authentication by use of a wireless communication medium such as an IC tag and an IC card, at a plurality of gateways which exist on a floor of an office building, there is such a case that communication with a wireless communication medium has to be realized in a very wide area, such as ID authentication due to communication with a wireless communication medium, at a number of places in an inside of a building.
On this account, for example, in order to carry out communication with a wireless communication medium in a very wide place, there is such a method that a very large side antenna is installed.
Alternatively, there is such a system that a number of wireless communication medium processing apparatuses, in each of which an antenna and a reading/writing section were combined, are installed, and these are all connected to and processed by a host which controls them in a concentrated manner (e.g., see, JP-A-2001-43326 publication).
FIG. 22 is a block diagram of a wireless communication medium processing apparatus in prior art.
As apparent from FIG. 22, this conventional wireless communication medium processing apparatus requires a number of reading/writing sections, and various control mechanisms are required such as synchronous control between these.
Alternatively, studied is such a system that a plurality of antennas are installed at a number of places, and antennas, which carry out communication with a wireless communication medium is switched arbitrarily, exclusively and processed, through a reading/writing section which is also used as a host, an antenna changeover switch which switches over which antenna is connected, among these antennas.
FIG. 23 is a block diagram of a wireless communication medium processing apparatus in prior art.
As apparent from FIG. 23, in this conventional wireless communication medium processing apparatus, there is such a necessity that an antenna to be connected is switched over sequentially and used.
Further, proposed are a device in which a plurality of antennas are connected to one reading/writing section and which carries out distribution on a transmission side and combining on a reception side, and so on. In addition, proposed are a device in which one reading/writing section is connected to a plurality of antennas for the purpose of expanding a communication range of an antenna, but the reading/writing section has a plurality of demodulation sections, and so on.
However, in conventional wireless communication medium processing apparatus and wireless communication medium processing system, a configuration for realizing communication with a wireless communication medium in a very wide area such as an office building and a large size shop, or at a plurality of places in this wide area has the following problems.
Firstly, in case that a size of an antenna was enlarged in order to cover a very wide area, there was such a problem that it is unrealistic and difficult to form an antenna with a size for covering, for example, an entire floor of a building, in a phase of its manufacturing, cost, strength etc.
For example, in a case described in FIG. 22, in case that a number of apparatuses, in each of which an antenna and a reading/writing section were combined, are disposed, and are connected to a host which controls them in a concentrated manner, a number of expensive reading/writing sections are required, and therefore, there is such a problem that a wireless communication medium processing apparatus becomes very too expensive. Further, each reading/writing section operates asynchronously and independently, and therefore, there was such a problem that, on the occasion that an ID code, which ware read out from a wireless communication medium through each antenna, is communicated from a reading/writing section to a host, it is out of synchronization, and erroneous recognition due to collision of data occurs. In addition, there is such a necessity that a plurality of reading/writing sections as electronic devices are disposed, and therefore, there occurred such a problem that, when any one of these reading/writing sections fails to operate properly, communication with a wireless communication medium becomes impossible at all, at a certain place. These synchronizing processing (i.e., phase lag of a signal to be processed between reading/writing sections with each other) etc. are big problems both in transmission and in demodulation, and collision occurs in case of reading a number of wireless communication media, etc., and there was such a problem that a tremendous processing circuit becomes necessary in order to avoid this.
Further, in a case described in FIG. 23, there was such a problem that, in case that a plurality of antennas are connected to a reading/writing section through an antenna changeover switch, individual antennas are switched over, and therefore, an antenna, which becomes active and is enabled to communicate with a wireless communication medium, is determined exclusively, and therefore, it is not possible to have all antennas operated simultaneously. For example, even in case that each antenna was disposed at a number of gateways which exist on an office floor, there was such a problem that it is not possible to carry out ID authentication by communication with a wireless communication medium at a plurality of gateways simultaneously. By this means, there was such a problem that it is simply possible to configure only a system which is disadvantageous and inconvenient.
Further, in case that a plurality of antennas were activated simultaneously in an antenna changeover switch, there is such a problem that RF signals, which were received by respective antennas, collide with each other, and it is not possible to carry out accurate demodulation in a reading/writing section, and adversely, there is such a problem that a transmission signal from the reading/writing section also causes a collision, and is not transmitted to each antenna accurately, and there was such a problem that it is not possible to carry out accurate communication with a wireless communication medium.
Further, in case of switching over an antenna to be activated by the antenna changeover switch, it is actually unknown that a wireless communication medium exists in a communication range of which antenna, and therefore, there is such a necessity that an antenna to be activated is switched over in sequence, in order to realize communication with a wireless communication medium as to which it is unknown where it exists, and processing is complicated. Alternatively, in case that a wireless communication medium moves, even if an antenna to be activated was switched over in sequence, a wireless communication medium does not exist in a communication range of an antenna which is activated for all time, and there was also such a problem that it is not possible to realize communication endlessly.
Further, there was also such a problem that noises are generated at the time of antenna switching.